Internal combustion engine



FIG. 1 is a front elevational view of an internal combustion engine according to a first embodiment of our new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a front left perspective view thereof.

The broken lines show in FIGS. 1-4, and 6 are for purposes of illustration and form no part of the claimed design. 

CLAIM The ornamental design for an internal combustion engine, as shown and described. 